Inferential sensors offer low cost alternatives for signal acquisition compared to hardware sensors whose inclusion may be difficult to implement in an engine in some instances. Furthermore, hardware sensors often indicate a bulk engine temperature that relates to an energy potential between a source and sink within the engine system and so do not capture the thermal state of certain engine regions, like the region near a combustion chamber, which can have a higher temperature and therefore exceed thresholds well before bulk temperature regions. When this is the case, useful energy may be inadvertently wasted that results in a suboptimal thermal management process.
In one example system, U.S. Pat. No. 7,237,513 selectively operates a coolant pump based on an engine operating state in order to shorten a heating time after a cold start. However, the system described uses a web sensor arranged in a web between an inlet valve and an outlet valve within the cylinder head to measure the temperature of the combustion chamber. As such, a sensor is used to measure the temperature in the cylinder head directly. In another example, U.S. Pat. No. 7,128,026 describes a method for influencing the heat balance of an internal combustion engine based on coolant temperatures. Therein, the system described is based on a bulk temperature measurement within the engine system and therefore may not represent various local engine temperatures, particularly in selected regions where the engine temperatures may be substantially higher.
The inventors have recognized disadvantages with the systems above and herein disclose an example system and method for operating a coolant pump independent of engine speed, and adjusting one or more parameters responsive to an inferred local metal temperature in the exhaust valve bridge of a cylinder head. In one particular example, the temperature estimator uses a trained neural network model to infer the exhaust valve bridge temperature of the aluminum material between the exhaust valve seats, which may have a higher local temperature than the bulk temperature measured by a sensor in some instances. Then, a controller may adjust the flow of coolant based on comparisons of the local temperature estimates to a temperature threshold and bulk or average engine temperature, which thereby allows the thermal load on the engine to be managed in accordance with the methods described.
The present description may provide several advantages. In particular, with an accurate metal temperature estimate, flow devices may be used to their full potential by not enforcing conservative conditional controls. In addition, the approach described allows a low cost alternative compared to methods that use a sensor directly in the region of the cylinder head, which presents packaging difficulties in the engine compartment and thereby increases the cost of production. Estimation of the exhaust valve bridge temperature also allows the real time characterization of parameters that cannot be measured directly using traditional hardware sensors. Furthermore, because local temperatures in this region may fluctuate dramatically, concerns related to traditional hardware sensor robustness over time may be substantially reduced. In addition, if the online estimator is implemented in a powertrain control module, the methods described allow for a reduction in the use of system storage and computational resources compared to other regressed physics-based models and conditionals.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings. It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.